Side Impact Sensor Systems

ABSTRACT

Side impact airbag system for a vehicle includes a side airbag arranged to deploy along a left or right side of the vehicle and an electronic crash sensor. The electronic crash sensor includes a housing, a mass arranged within the housing to be movable in a lateral direction relative to the housing in response to lateral accelerations of the housing, and a control mechanism for controlling deployment of the side airbag and which is responsive to the motion of the mass only in the lateral direction. The housing is mounted in such a position and a direction as to sense an impact into a side of the vehicle resulting in lateral acceleration of the housing. The electronic crash sensor may generate a signal representative of the movement of the mass.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/174,837 filed Jul. 5, 2005 which is a continuation of U.S. patentapplication Ser. No. 10/963,390 filed Oct. 12, 2004, now U.S. Pat. No.7,025,379, which is a continuation of U.S. patent application Ser. No.10/768,791 filed Jan. 30, 2004, now U.S. Pat. No. 7,052,038, which is acontinuation of U.S. patent application Ser. No. 09/435,045 filed Nov.8, 1999, now U.S. Pat. No. 6,685,218, which is a continuation-in-part ofU.S. patent application Ser. No. 09/114,962 filed Jul. 14, 1998, nowU.S. Pat. No. 6,419,265 which is a continuation-in-part of U.S. patentapplication Ser. No. 08/101,017 filed Sep. 16, 1993, now U.S. Pat. No.5,842,716.

This application is related to U.S. patent application Ser. No.11/058,337 filed Feb. 15, 2005, now U.S. Pat. No. 7,070,202, on thegrounds that they include common subject matter.

All of the above-mentioned applications are incorporated herein byreference

FIELD OF THE INVENTION

This invention relates to side impact crash sensors for vehicles andside impact airbag systems.

BACKGROUND OF THE INVENTION

Self-contained airbag systems contain all of the parts of the airbagsystem within a single package, in the case of mechanicalimplementations, and in the case of electrical or electronic systems,all parts except the primary source of electrical power and, in somecases, the diagnostic system. This includes the sensor, inflator andairbag. Potentially these systems have significant cost and reliabilityadvantages over conventional systems where the sensor(s), diagnostic andbackup power supply are mounted separate from the airbag module. Inmechanical implementations in particular, all of the wiring, thediagnostic system and backup power supply are eliminated. In spite ofthese advantages, self-contained airbag systems have only achievedlimited acceptance for frontal impacts and have so far not beenconsidered for side impacts.

The “all-mechanical” self-contained systems were the first to appear onthe market for frontal impacts but have not been widely adoptedpartially due to their sensitivity to accelerations in the vertical andlateral directions. These cross-axis accelerations have been shown toseriously degrade the performance of the most common all mechanicaldesign that is disclosed in Thuen, U.S. Pat. No. 4,580,810. Both frontaland side impact crashes frequently have severe cross-axis accelerations.

Additionally, all-mechanical self contained airbag systems, such asdisclosed in the Thuen patent, require that the sensor be placed insideof the inflator which increases the strength requirements of theinflator walls and thus increases the size and weight of the system. Onesolution to this problem appears in Breed, U.S. Pat. No. 4,711,466, buthas not been implemented. This patent discloses a method of initiatingan inflator through the use of a percussion primer in combination with astab primer and the placement of the sensor outside of the inflator. Onedisadvantage of this system is that a hole must still be placed in theinflator wall to accommodate the percussion primer that has its ownhousing. This hole weakens the wall of the inflator and also provides apotential path for gas to escape.

Another disadvantage in the Thuen system that makes it unusable for sideimpacts, is that the arming system is sealed from the environment by anO-ring. This sealing method may perform satisfactorily when the moduleis mounted in the protected passenger compartment but it would not besatisfactory for side impact cases where the module would be mounted inthe vehicle door where it can be subjected to water, salt, dirt, andother harsh environments.

Self-contained electrical systems have also not been widely used. Whenairbags are used for both the driver and the passenger, self-containedairbag systems require a separate sensor and diagnostic for each module.In contrast to mechanical systems, the electronic sensor and diagnosticsystems used by most vehicle manufacturers are expensive. Thisduplication and associated cost required for electrical systemseliminates some of the advantages of the self contained system.

Sensors located in the passenger compartment of a vehicle can catch mostairbag-required crashes for frontal impacts, particularly if theoccupants are wearing seatbelts. However, researchers now believe thatthere are a significant number of crashes which cannot be sensed in timein the passenger compartment and that this will require the addition ofanother sensor mounted in the crush zone (see, for example, Breed, D.S., Sanders, W. T. and Castelli, V. “A Critique of Single PointSensing”, Society of Automotive Engineers Paper No. 920124). If true,this will eventually eliminate the use of self-contained airbag systemsfor frontal impacts.

Some of these problems do not apply to side impacts mainly because sideimpact sensors must trigger in a very few milliseconds when there is nosignificant signal at any point in the vehicle except where the car iscrushing or at locations rigidly attached to this crush zone. Eachairbag system must be mounted in the crush zone and generally will haveits own sensor. Self contained airbag systems have heretofore not beenused for occupant protection for side impacts which is largely due tothe misconception that side impact sensing requires the use of elongatedswitches as is discussed in detail in U.S. Pat. No. 5,231,253,incorporated by reference herein. These elongated prior art side impactcrush-sensing switches are not readily adaptable to the more compactself-contained designs. The realization that a moving mass sensor wasthe proper method for sensing side impacts has now led to thedevelopment of the side impact self contained airbag system of thisinvention. The theory of sensing side impacts is included in the '253patent referenced above.

In electro-mechanical and electronic self-contained modules, the backuppower supply and diagnostic system are frequently mounted apart from theairbag system. If a wire is severed during a crash but before the airbagdeploys, the system may lose its power and fail to deploy. This is morelikely to happen in a side impact where the wires must travel inside ofthe door. For this reason, mechanical self-contained systems have asignificant reliability advantage over conventional electrical systems.

Finally, the space available for the mounting of airbag systems in thedoors of vehicles is frequently severely limited making it desirablethat the airbag module be as small as possible. Conventional gasgenerators use sodium azide as the gas generating propellant. Thisrequires that the gas be cooled and extensively filtered to remove thesodium oxide, a toxic product of combustion. This is because the gas isexhausted into the passenger compartment where it can burn an occupantand is inhaled. If the gas is not permitted to enter the passengercompartment, the temperature of the gas can be higher and the productsof combustion can contain toxic chemicals, such as carbon dioxide.

These and other problems associated with self-contained airbag systemsand side impact sensors are solved by the invention disclosed herein.

OBJECTS AND SUMMARY OF THE INVENTION

This invention is concerned with a novel self-contained airbag systemfor protecting occupants in side impacts. It is also concerned with thesensors used either with self-contained modules or apart from the airbagmodule. This may be accomplished by using the sensors described in U.S.Pat. No. 5,231,253 referenced above, along with other improvementsdescribed in detail below. This invention is secondarily concerned withapplying some of the features of the novel side impact system to solvingproblems of prior art mechanical airbag systems, e.g., those discussedabove. The sensitivity to cross axis accelerations of current allmechanical airbag systems, for example, is solved in the presentinvention, as discussed in U.S. Pat. No. 5,233,141, incorporated byreference herein, through the substitution of a hinged sensing elementfor the ball sensing mass in the Thuen patent.

Problems resulting from the hole in the inflator wall when a percussionprimer is used as in Breed, U.S. Pat. No. 4,711,466, are solved in thepresent invention through the placement of sensitive pyrotechnicmaterial in a cavity adjacent to the outside wall of the inflator andthen using shock from a stab primer to initiate the pyrotechnic materialand thus the inflator. An alternate solution, as discussed below, is tomake the size of the hole created in the inflator by the action of thestab primer small so that the total quantity of gas which escapes intothe sensor is small compared with the quantity of gas used to inflatethe airbag.

Finally, in self-contained airbag system disclosed herein, provision ismade to exhaust the gas outside of the passenger compartment, into thevehicle doors, or other side areas of the vehicle. This permits the useof higher gas temperatures and alternate propellant formulations, suchas nitro-cellulose, which produce toxic combustion products. Both ofthese changes reduce the size, weight and cost of the system.

The sensors used here are either electronic, electro-mechanical ormechanical but all have a movable mass where the motion of the mass issensed either electronically or mechanically.

Principal objects and advantages of one or more of the inventionsdisclosed herein are:

-   1. To provide a self contained side impact occupant protection    airbag system incorporating the advantages of a movable mass sensor    resulting in a low cost, compact airbag system.-   2. To provide a frontal impact all mechanical airbag system    incorporating a hinged sensing mass to eliminate the effects of    cross-axis accelerations on the operation of the sensor.-   3. To provide a method of minimizing the leakage of the inflator    gases out of the inflator portion of a self contained airbag system    into the sensor portion and the associated problems.-   4. To provide a side impact airbag system which utilizes the crush    of the vehicle side to arm the sensor and motion of a sensing mass    to initiate deployment.-   5. To provide a method of hermetically sealing a self contained    airbag system while permitting an external force to be used to arm    the system.-   6. To provide a more compact self contained side impact airbag    system by providing for the exhausting of the airbag gas into the    vehicle door or side, therefore permitting the use of higher    temperature gas and propellants which would otherwise not be viable    due to their toxic products.-   7. To provide an all-mechanical airbag system utilizing a    cantilevered firing pin spring which also provides the biasing force    on the sensing mass thereby providing a simplified design.-   8. To provide an all-mechanical airbag system with a thin sensor    mounted outside of the inflator housing but in line with it to    reduce the size of the system and permit the use of conventional    inflator designs.-   9. To provide a highly reliable side impact occupant protection    electro-mechanical self-contained airbag system.-   10. To provide a highly reliable side impact occupant protection    electronic self contained airbag system.-   11. To provide a method of obtaining the power for an electrical    self contained airbag system from other components within the door    thereby minimizing the requirement for separate wiring for the    airbag system.-   12. To provide a power supply within the self contained module and a    simplified diagnostic system for an electrical self contained airbag    system.-   13. To provide a self contained airbag system design that permits    the arming of the sensor after it has been mounted onto the vehicle    but before the inflator is mounted to provide greater safety against    unwanted deployments.-   14. To provide an electronic, electro-mechanical or mechanical    sensor for use with either a self-contained airbag system or    conventional airbag system wherein the sensor system senses the    acceleration of the vehicle member on which it is mounted and where    in the sensed acceleration is the crush zone acceleration and is    used to control the deployment of the side airbag.

Other objects and advantages will become apparent from the discussionbelow.

In order to achieve at least one of the objects noted above, a firstembodiment of a vehicle in accordance with the invention has alongitudinal axis between a front and rear of the vehicle such that alateral direction is defined perpendicular to the longitudinal axis, aright side and a left side spaced apart in the lateral direction, and aside impact airbag system which includes a side airbag arranged todeploy along the left or right side of the vehicle and an electroniccrash sensor. The electronic crash sensor includes a housing, a massarranged within the housing in a position and direction so as to bemovable in the lateral direction relative to the housing in response tolateral accelerations of the housing, and a control mechanism forcontrolling deployment of the side airbag and which is responsive to themotion of the mass only in the lateral direction. The housing is mountedin such a position and a direction as to sense an impact into a side ofthe vehicle resulting in lateral acceleration of the housing, e.g. by anappropriate mounting mechanism.

The electronic crash sensor may generate a signal representative of themovement of the mass. It may include a microprocessor and an algorithmfor determining whether movement over time of the mass results in acalculated value which is in excess of a threshold value. The housingmay be arranged in a door on the right or left side of the vehicle.

Another embodiment of a vehicle in accordance with the inventionincludes a longitudinally extending outer skin arranged on a side of thevehicle, a system housing arranged inward of the outer skin and havingan opening facing a portion of a passenger compartment of the vehicle,an inflatable airbag arranged in the system housing, an inflatorarranged in connection with the system housing, and an electronic sensorsystem for detecting an impact into a side of to the vehicle. Theelectronic sensor system includes a sensor housing and a mass arrangedin the sensor housing and movable relative to the sensor housing inresponse to acceleration, movement of the mass relative to the sensorhousing providing an indication of a side impact for which deployment ofthe airbag is desired. The inflator is actuated in response to adetected side impact by the sensor system in order to expel the airbagthrough the opening into the passenger compartment. The sensor system isarranged such that the inflator is actuated and the airbag is inflatedand expelled through the opening into the passenger compartment based onmovement of the mass.

The vehicle may include an inner skin having a portion alongside thepassenger compartment of the vehicle, in which case, the system housingis arranged between the outer and inner skins of the vehicle and theopening of the system housing is situated on an inward facing side ofthe system housing. The system housing is mounted such that the openingfaces an outward facing surface of the inner skin alongside thepassenger compartment.

The inflator may be arranged at least partially within the systemhousing. It may also be arranged on a side of the system housingopposite the side on which the opening is formed. The inflator mayinclude a plurality of gas orifices, in which case, the airbag isinflated by directing inflating gas through the orifices into theairbag.

The system housing can include a base wall having an aperture in whichthe inflator is partially received and flanged walls extending fromedges of the base wall and forming the opening. The sensor system may bearranged on a side of the system housing opposite the side on which theopening is formed. It may also be arranged proximate the inflator oralongside the inflator. It may also be arranged outside of and on theinflator.

A method for deploying a side airbag of a vehicle having an outer skinin accordance with the invention includes providing a system housinghaving an opening, mounting the system housing with the opening facing aportion of a passenger compartment of the vehicle, arranging aninflatable airbag in the system housing, arranging an inflator inconnection with the system housing, electronically sensing a side impactby detecting motion of a mass situated in a sensor housing relative tothe sensor housing and in response to acceleration, actuating theinflator in response to the detected side impact to expel the airbagthrough the opening in the system housing into the passengercompartment, and coupling the mass to the inflator such that theinflator is actuated always upon sensing of the side impact above acertain magnitude in a direction perpendicular to the outer skin of thevehicle.

Optionally, the system housing is arranged between the outer skin and aninner skin of the vehicle such that the opening of the system housing ison an inward facing side of the system housing, the system housing beingmounted such that the opening faces an outward facing surface of theinner skin alongside the passenger compartment. When the outer and innerskins form a door, the system housing may be arranged in the door.

Another embodiment of a vehicle in accordance with the inventionincludes a longitudinally extending outer skin arranged on a side of thevehicle, a system housing arranged inward of the outer skin and havingan opening facing a portion of a passenger compartment of the vehicle,an inflatable airbag arranged in the system housing, an inflatorarranged in connection with the system housing, and an electronic sensorsystem for detecting an impact into a side of the vehicle and comprisinga sensor housing and a mass arranged in the sensor housing and movablerelative to the sensor housing in response to acceleration. Movement ofthe mass relative to the sensor housing provides an indication of a sideimpact for which deployment of the airbag is desired. The inflator isactuated in response to a detected side impact by the sensor system inorder to expel the airbag through the opening into the passengercompartment. Moreover, the inflator is actuated directly by the sensorsystem whenever the sensor system provides an indication of the sideimpact in a direction perpendicular to the outer skin of the vehicle forwhich deployment of the airbag is desired.

In another embodiment of a vehicle in accordance with the invention, theside impact airbag system comprises an airbag and inflator assemblyincluding an airbag housing, at least one inflatable airbag arranged inthe airbag housing such that when inflating, each airbag is expelledfrom the airbag housing into a passenger compartment of the vehicle, anda squib arranged to initiate inflation of the airbag(s). An electronicsensor system controls inflation of the airbag(s) upon a determinationof a crash into the left or right side of the vehicle requiringinflation thereof and includes a sensor having a sensor housing arrangedin a door or between inner and outer side panels along a left or rightside of the vehicle and a movable sensing mass arranged within andmovable in a lateral direction relative to the sensor housing inresponse to lateral accelerations of the sensor housing, and at leastone electronic component responsive to the motion of the mass andarranged in a circuit with the squib for causing ignition of the squib.The sensor housing is arranged in such a position and a direction in thedoor or between the inner and outer panels along the left or right sideof the vehicle as to cause movement of the mass upon an impact into theleft or right side of the vehicle resulting in lateral acceleration ofthe sensor housing.

The electronic component may be a micro-processor containing analgorithm arranged to generate a time-varying signal representative ofmovement of the mass in the lateral direction, analyze the signalrepresentative of the movement of the mass and generate a deploymentsignal based thereon.

The sensor housing may be mounted onto a side door of the vehicle oronto a side of the vehicle between centers of front and rear wheels ofthe vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the followingnon-limiting drawings in which:

FIG. 1 is a perspective view with certain parts removed of an allmechanical self contained airbag system for mounting on the side of avehicle to protect occupants in side impacts;

FIG. 2 is a cross sectional view of the apparatus of FIG. 1 taken alongline 2-2;

FIG. 3 is an enlarged fragmentary view of the sensing mass and attachedlever arm extending from the D-shaft prior to rotation of the sensingmass incident to a crash as adapted to the all mechanical system of U.S.Pat. No. 4,580,810;

FIG. 4 is a similar view as FIG. 3 showing the sensing mass rotated as aresult of a crash;

FIG. 5 is a view of the apparatus shown in FIG. 4 taken along line 5-5and rotated 90 degrees to the right;

FIG. 6 is a cross section view of a sensor for use in an all mechanicalsystem where the sensor is mounted outside of the inflator housing,shown in an unarmed or safe position prior to assembly with an inflator;

FIG. 7 is a cross section view of the sensor of FIG. 6 shown mounted onan inflator, shown in a fragmentary view, after it has triggered inresponse to a vehicle crash;

FIG. 8 is a cross section view of a through bulkhead initiation systemadapted to a mechanical self contained airbag system;

FIG. 9 is a perspective view of a mechanical self contained airbagsystem using a crush sensing arming system, shown in the state before acrash occurs;

FIG. 9A is a blowup with certain parts removed showing a portion of thesensor shown in FIG. 9 in the unarmed position;

FIG. 10 is a cross section view of the apparatus of FIG. 9 taken alongline 10-10 showing the crush sensing arming system after it has beenactivated by vehicle crush but before the sensing mass of thediscriminating sensor has begun to move;

FIG. 10A is an enlarged view with certain parts removed showing aportion of the sensor shown in FIG. 10 in the armed position;

FIG. 11 is a cross section view of the apparatus of FIG. 9, also takenalong line 10-10, showing the crush sensing arming system after it hasbeen activated by vehicle crush and showing the sensing mass of thediscriminating sensor after it has moved and released the firing pin,triggering the inflation of the airbag;

FIG. 11A is an enlarged view with certain parts removed showing aportion of the sensor shown in FIG. 11 in the fired position;

FIG. 12 is a perspective view of a side impact airbag systemillustrating the placement of the airbag vents in the door panel and theexhausting of the inflator gases into the vehicle door and also showingthe use of a pusher plate to adjust or account for the mismatch betweenthe point of impact of an intruding vehicle and the sensor of a selfcontained side impact airbag system;

FIG. 13 is a cross section view of a self-contained side impact airbagsystem using an electro-mechanical sensor;

FIG. 14 is a cross section view of a self-contained side impact airbagsystem using an electronic sensor;

FIG. 15 is a schematic of the electric circuit of an electro-mechanicalor electronic self contained side impact airbag system; and

FIG. 16 is a side view of a vehicle showing the preferred mounting oftwo self contained airbag modules into the side of a coupe vehicle, oneinside of the door for the driver and the other between the inner andouter side panels for the rear seat passenger.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the accompanying drawings wherein like reference numeralsrefer to the same or similar elements, FIGS. 1 and 2 show anall-mechanical self-contained airbag system for mounting on the side ofa vehicle to protect occupants in side impacts in accordance with theinvention which is designated generally as 100. The airbag system 100contains one or more inflatable airbags 110, an inflator assembly 120, amounting plate 160 for mounting the airbag system 100 on the side of thevehicle and a sensor assembly 140 mounted to the inflator assembly 120.The sensor assembly 140 contains a rotatable, substantially planarsensing mass 141 and a cantilevered biasing spring 142 which performsthe dual purposes of biasing the sensing mass 141 toward its at restposition shown in FIG. 2 and also providing the energy to the firing pin143 required to initiate a stab primer 122 as further described below.The sensing mass 141 contains a firing pin spring-retaining portion 144that restrains the firing pin 143 during the sensing time and releasesit when the sensing mass 141 has rotated through the sensing angle. Theretaining portion 144 is an L-shaped descending part formed on a planarsurface of the sensing mass 141 and defines a cavity for retaining anend of the spring 142.

As shown in FIG. 1, the mounting plate 160 constitutes a housing for theairbag system 100, i.e., it has a bottom wall and flanged side wallsextending from edges of the bottom wall which define an interior spacein which the airbag(s) 110 and a portion of the inflator assembly 120are arranged. The bottom wall is substantially flat and has asubstantially circular aperture. The inflator assembly 120 is positionedin the aperture so that a portion thereof extends on either side of thebottom wall (See FIG. 2). Also as shown in FIG. 2, the housing of theinflator assembly 120 includes a flange that abuts against the bottomwall of mounting plate 160 around the aperture. As will be appreciatedby those skilled in the art, the flanged side walls of the mountingplate 160 are positioned around a panel on the side of the vehicle,e.g., a blow-out panel in the side door, so that the airbag(s) 110 wheninflating will be expelled from the interior space defined by themounting plate 160 into the passenger compartment of the vehicle. Themounting plate 160 may thus be mounted to a frame of the side door byattaching the flanged side walls to the frame or attaching anotherportion of the mounting plate to the frame. The actual manner in whichthe mounting plate 160 is mounted in the side door, or on the side ofthe vehicle, is not critical so long as the mounting plate 160 ispositioned to allow the airbag(s) 110 to be expelled from the interiorspace into the passenger compartment. Mounted as such, the sensorassembly 140 will be most proximate the exterior of the vehicle with theairbag 110 most proximate the passenger compartment of the vehicle.

The sensing mass 141 is connected to the housing 101 of sensor assembly140 through a hinge 145 at one end whereby the opposed end isunrestrained so that the sensing mass 141 rotates about the hinge 145.In view of the mounting of the airbag system 100 on the side of thevehicle, hinge 145 defines a rotation axis which is perpendicular to thelongitudinal direction of travel of the vehicle (x) as well asperpendicular to a direction (y) transverse to the longitudinaldirection of travel of the vehicle, i.e., it is a vertical axis (z).

The sensor housing 101 includes opposed housing wall portions 146 and148, a bottom cover 150 and a top cover 151 which is connected to,mounted on or the same part as a top cover 121 of the inflator assembly120. The sensor housing 101 is filled with air and sealed (whenappropriately mounted to the inflator assembly 120 whereby a smallorifice 127 in top cover 151 is closed by the inflator assembly 120) soas to maintain a constant air density regardless of the ambienttemperature or pressure. The sensor housing walls 146,148 and sensingmass 141 are preferably molded along with the hinge 145 in a singleinsert molding operation to provide a careful control of the dimensionsof the parts and particularly of a clearance 152 between the walls146,148 and the sensing mass 141 for the reasons described below.

The inflator assembly 120 comprises a stab primer 122, igniter mix 130associated with the stab primer 122, one or more propellant chambers 123containing propellant 124 and a series of cooling and filtering screens125. In the particular design shown in FIGS. 1 and 2, the stab primer122 has been placed inside of an igniter housing portion 126 of thehousing of the inflator assembly 120, the housing of the inflatorassembly being formed by opposed housing sections 121 and 129. Housingsections 121 and 129 cooperate to define a substantially cylindricalhousing for the inflator assembly 120. Housing section 121 is coupled tothe sensor housing 101. Exit orifices 128 are provided in the housingsection 129 to allow the gas generated by the burning propellant 124 toflow into the airbag 110 to inflate the same. A small orifice 127 hasbeen left open in the top cover 151 of the housing 101 of the sensorassembly 140, as well as the housing section 121, to allow the firingpin 143 to enter into the interior of the inflator assembly 120 andcause initiation of the stab primer 122. The stab primer 122 is from afamily of the most sensitive stab primers requiring less than 25 in-ozof energy for activation. The standard M55 military detonator is amember of this class and has been manufactured in very large quantitiesduring war time. For the purposes of this disclosure, the term primerwill be used to represent both primers and detonators. The small orifice127 will permit some gas to enter the sensor housing 101 during the timethat the propellant 124 is burning and inflating the airbag 110 butsince its area is less than 1% of the area of the exit orifices 128through which the generated gas enters the airbag 110, less than 5% ofthe generated gas will pass into the sensor. Naturally, a larger orificecould be used but in all cases the amount of gas which passes into thesensor housing 101 will be less than 10% of the total gas generated.Since this gas will be hot, however, it will destroy the sensor assembly140 and leak into the door. In another implementation discussed below, athrough bulkhead initiation system is used to prevent any gas frompassing into the sensor assembly from the inflator assembly.

During operation of the device, sensing mass 141 rotates relative tosensor housing 101 in the direction of the arrow (shown in FIG. 2) underthe influence of the acceleration with its motion being retarded by thebiasing spring 142 and the gas pressure forces. Upon a sufficientrotation, biasing spring 142 is released from the retaining portion 144of the sensing mass 141 and moves toward the inflator assembly 120 andthe firing pin 143 formed in connection with the biasing spring 142moves to impact stab primer 122 which burns and ignites the igniter mix130. The igniter mix, which is typically composed of boron and potassiumnitrate, then ignites the propellant 124 that burns and generates gas.The gas then flows through exit orifices 128 into the inflatable bag110, inflating the bag.

In the embodiment shown in FIGS. 1 and 2, the stab primer 122 has beenlocated in the center of the inflator housing. This is the conventionallocation for electrical primers in most driver's side inflator designs.The sensor is placed adjacent and in line with the inflator permittingthe use of conventional inflator designs which minimize the size,complexity and weight of the inflator. The sensing mass 141 isapproximately of square shape and the sensor housing 101 is madecircular to mate with the inflator design.

In the particular design shown in FIGS. 1 and 2, a burning propellantinflator design was illustrated. Naturally, other propellanttechnologies such as a stored gas or hybrid (a combination of stored gasand propellant) could have been used without departing from theteachings of this invention.

It will be appreciated by those skilled in the art that since the airbagsystem 100 is designed to activate in side impacts, the sensing mass 141is arranged for movement in a direction perpendicular to the sides ofthe vehicle, i.e., perpendicular to the longitudinal direction of travelof the vehicle, or in a pivoting movement about a vertical pivot axis.In this manner, the acceleration of the sensor housing 101 inward intothe passenger compartment (that is, acceleration in a lateral directionor lateral acceleration since the passenger compartment is inward fromthe sensor housing relative to the side of the vehicle in theillustrated embodiment) resulting from a crash into the side of thevehicle, will cause the sensing mass 141 to move or pivot outward towardthe impacting object thereby releasing its hold on the biasing spring142.

FIG. 3 shows a fragmentary view of a sensing mass 341 and an attachedlever arm 356 extending from a D-shaft 358 prior to rotation of thesensing mass incident to a crash as adapted to the all-mechanical systemof Thuen, U.S. Pat. No. 4,580,810. This figure corresponds to FIG. 6 ofthe Thuen patent and shows the improved sensing mass design. FIG. 4shows the same view as FIG. 3 with the sensing mass rotated, against theforce from spring 360 acting on ball 470, into the actuating positionwhere it has released the firing pin to initiate deployment of theairbag. FIG. 4 corresponds to FIG. 7 in the '810 patent. FIG. 5 is aview taken along line 5-5 of FIG. 4 and shows the shape of the sensingmass 341. Sensing mass 341 is retained in sensor housing 338, by cover339, and rotates with D-shaft 358. This rotation is facilitated bypivots 371, which form part of the D-shaft, and pivot plates 370. Inthis manner, the sensing mass 341 is hinged to the sensor housing 338permitting only rotational motion and rendering the sensor insensitiveto the effects of cross-axis accelerations. In this embodiment, sensingmass 341, lever arm 356, ball 470, pin 469 and the D-shaft 358 are allmade as one part that reduces the cost of the assembly. Naturally, theycould be made as separate parts and assembled. When D-shaft 358 rotatesthrough a sufficient angle, it releases firing pin 336 in the samemanner as shown in FIGS. 8 and 9 of the '810 patent. The motion of thesensing mass 341 is undamped since the clearance between the sensingmass 341 and sensor housing 338 is sufficiently large so as to minimizethe flow resistance of the air as the mass rotates. Naturally, inanother implementation, the mass could be redesigned to have its motiondamped by the flow of a gas in the manner shown in FIGS. 1 and 2 above.Also, two sensor systems of the type disclosed in FIGS. 3-5 can be usedin the all-mechanical system in a similar way as shown in the '810patent.

The all-mechanical system as depicted in FIGS. 3-5 requires that aspecial inflator be designed to accommodate the sensor within itshousing. There has already been a substantial investment in tooling andproduction facilities for electrically actuated inflators by severalinflator manufacturers. Also, substantial reliability statistics havebeen accumulated on these inflator designs through the hundreds ofmillions of miles that airbag equipped vehicles have traveled. It isdesirable to build on this base with new systems that can be done usingthe sensor designs of this invention as depicted in FIGS. 6 and 7. Thissensor design is adapted to be attached to a standard electricalinflator design where a stab primer 691 is used in place of theelectrically actuated squib normally used.

The sensor-initiator is shown generally as 600 in FIG. 6. In a similarmanner as described above, sensing mass 641 rotates in sensor housing630 during a crash against the force provided by a cantilevered biasingspring 662 until a D-shaft 658 has rotated sufficiently to release afiring pin 636. Once released, firing pin 636 is propelled by firing pinspring 635 and impacts primer 691 to initiate deployment of the airbag.A washer 692 having an orifice is arranged between the primer 691 andthe sensor housing 630 to minimize the leakage of inflator gases fromthe inflator 690 while the propellant is burning (FIG. 7). In thismanner, the sensor does not have to be constructed of strong materialsas discussed in the above referenced patent.

In one configuration of a self-contained system, the sensor assembly andthe airbag and inflator assembly are kept separate until mounted ontothe vehicle. In this case, the sensor is mounted using an appropriateapparatus (not shown) to the steering wheel after the wheel is mountedto the vehicle. Then, the airbag module is assembled to the steeringwheel. In this case, the sensor is armed after it has been installedonto the vehicle through the use of arming screw 670. The inflator isonly brought into contact with the sensor after the sensor has beenmounted onto the vehicle, thus minimizing the chance of an inadvertentactuation prior to installation. To arm the sensor, arming screw 670 isrotated after the sensor is mounted onto the steering wheel causing itto move downward in its housing 674. This removes the retaining cylinder673 from blocking the motion of locking ball 675 that removes a lock onthe firing pin. As long as ball 675 remains locking the firing pin 636,rotation of the mass 641 will not release the firing pin and the sensoris unarmed. Additional apparatus, not shown, can be used to prevent theassembly and disassembly of the sensor from the steering wheel unlessthe arming screw 670 is in the unarmed position. Also, interferencebetween the head 680 of the arming screw 670 and the surface 693 of theinflator 690 prevents assembly of the inflator and airbag module to thesteering wheel until the sensor has been armed. Thus, in this verysimple manner, an inexpensive all-mechanical airbag system can be madeusing standard inflator designs with minor modifications.

In FIGS. 1 and 2, the stab primer was shown as part of the inflatorassembly, i.e., contained within the housing of the inflator assemblydefined by housing portions 121,129. On the other hand, in FIG. 8, across section view of a through bulkhead initiation system adapted to amechanical self-contained airbag system is illustrated. In this case,the stab primer 822 is instead part of a sensor assembly 840, i.e.,arranged in the sensor housing on the bottom cover thereof if present,and when the stab primer 822 is initiated by a firing pin 842 formed inconjunction with a cantilevered, biasing spring (as in the embodimentshown in FIGS. 1 and 2), it creates a shock on one side of an inflatorhousing wall 821 which is transmitted through the wall 821 and interactswith a shock sensitive pyrotechnic mix 829 which has been placed into acavity 805 in the igniter mix. Inflator housing wall 821 is alongsidethe bottom cover of the sensor housing, but in the alternative, theinflator housing wall may be the same as the bottom cover of the sensorhousing. This through-bulkhead initiation system and the particularpyrotechnic mix formulation is well known to ordinance engineers whereit has been applied to military devices. Such a system has not beenused, however, in airbag systems. In this manner, a hole is not openedbetween the sensor assembly and the inflator assembly and the gas isprevented from leaking into the sensor assembly.

In FIG. 9, a perspective view of a mechanical self-contained airbagsystem using a crush sensing arming system designated generally as 950is shown in the state before a crash occurs. In this embodiment, thesensor is armed when the vehicle door skin, or side skin, is crushed towhere it impacts a curved impact plate, not shown, which then impacts asensor can 970 surrounding the sensor assembly and displaces an outercover 951 thereof relative to a sensor housing 901. Sensor can 970 has atubular wall arranged partially alongside a housing section of theinflator assembly to thereby define a closed space between the outercover 951 and an outer surface of the inflator assembly in which thesensor assembly is positioned. The sensor crush-sensing outer cover 951has a slight arcuate shape so that it oil-cans or deflects downwardpressing on lever 971 through a hemi-spherical pusher member 979. Lever971 is hingedly mounted at one end thereof to enable it to rotate aboutits attachment point 972 to the sensor housing 901 and causes lever 973to also rotate about its pivot point 974 on the sensor housing 901 byvirtue of hinge 978. As shown in FIG. 9A, an end 975 of lever 973extends through an aperture 904 in a wall of the sensor housing 901 andserves to restrain the sensing mass 941 from any movement. The rotationof lever 973 causes the end 975 of lever 973 to pull out of the sensorhousing 901 where it was detenting the sensing mass 941 and preventingthe sensing mass 941 from rotating to the degree necessary to release afiring pin spring 942. The sensing mass 941 is then free to move andrelease the firing pin spring 942 causing the firing pin spring 942 toignite the stab primer in the inflator assembly, either by contacttherewith or by pressure against the inflator assembly housing (seeabove) causing inflation of the airbag (FIG. 11A). Thus, until thesensor experiences a crushing force from the crash, the airbag systemcannot deploy. The sensing mass 941, firing pin spring 942, inflatorassembly and airbag may have the same structure as described above withreference to FIGS. 1 and 2. Other features of any of the disclosedembodiments not inconsistent with the embodiments shown in FIGS. 9-11Amay also be incorporated therein.

Levers 971 and 973 are joined together by hinge 978 and can be made froma single piece of material. In this case, the hinge would be formedeither by a coining or stamping operation or by a milling operation.Naturally, the two levers need not be joined together.

This provides a sensor system that requires the occurrence of twoenvironments that are always present in a crash, crush and velocitychange. The crush sensing outer cover 951 is designed to respond and armthe sensor when impacted from any reasonable direction by an impactplate, e.g., the curved impact plate discussed above, which is likely tooccur in a crash. For many vehicles, the crush may not reach the sensorat the time that deployment is required. In the case where two systemsare used on each side of the vehicle, for example, and an impact occursat the A-pillar, the rear seat system may not experience crush in time.The arming system shown in FIG. 9 could still be used where the armingwould occur when the system is mounted onto the vehicle instead of whenthe crash occurs. In this case, the curved impact plate would not benecessary and the deflection of the sensor cover 951 would occur eitherduring the mounting process or by a separate operation after the systemis mounted.

FIG. 10 is a cross section view of the apparatus of FIG. 9 taken alongline 10-10 and FIG. 10A is an enlarged, partial view thereof showing thecrush sensing outer cover 951 and lever system after end 975 has movedout of aperture 904 as a result of crush of the vehicle but before thesensing mass 941 of the discriminating sensor has begun to move. FIG. 11is a similar view of the apparatus of FIG. 10 but shows the sensing mass941 of the discriminating sensor after it has moved and released firingpin spring 942, triggering inflation of the airbag.

The motion of the sensing mass 941 is damped by the requirement that airmust flow between the sensing mass and the housing in the mannerdescribed in more detail in the '253 patent referenced above. Naturally,other damping methods such as magnetic damping could also be used.

In the case of FIG. 9, the sensor is entirely surrounded by a metal can970 that is formed by a drawing process. The sensor can 970 is attachedto the inflator assembly; more particularly, the sensor can 970 isattached to one or more housing sections thereof. The attachment of thesensor can 970 to the inflator assembly or housing section(s) thereof isachieved using structural adhesive 990 such as a urethane or epoxycompound. In this manner, the sensor is hermetically sealed.

The term hermetic seal as used herein means a seal which will not permitthe passage of any significant amount of moisture or other contaminantsinto the interior of the self-contained airbag module and further willnot permit the passage of gas into or out of the sensor housing ofsufficient quantity as to change the gas density by more than about 5%at any time over the life of the vehicle. Each vehicle manufacturer hasan accelerated life test that can be used along with appropriate sensortesting equipment to test the sensor seals according to this definition.Typical O-ring seals are not hermetic by this definition howeverproperly designed plastic and metal welded seals and epoxy and urethaneseals are hermetic.

FIG. 12 is a perspective view of a side impact airbag systemillustrating the placement of the airbag vents in the door panel and theexhausting of the inflator gases into the vehicle door 1200 and alsoshowing the use of a pusher plate 1201 to account for the mismatchbetween the point of impact of an intruding vehicle (or other object)and the sensor of a self-contained side impact airbag system 1220. Thepusher plate 1201 is shown attached to the main structural door beam1202 in this illustration but other mounting systems are also possible.The airbag system 1220 is shown between the inner panel 1230 and theouter panel 1240 of the door 1200.

The pusher plate 1201 is dimensioned and installed in the door 1200 sothat during a side impact to any portion of the side of the vehiclewhich is likely to cause intrusion into the passenger compartment andcontact an occupant, the pusher plate will remain in a substantiallyundistorted form until it has impacted with the sensor causing thesensor to begin deployment of the airbag. In this implementation, anon-sodium azide propellant, such as nitro-cellulose, is used and thegas is exhausted into the door though a pair of orifices. The airbagsystem 1220 may be any of those disclosed herein.

As shown in FIG. 12, the pusher plate 1201 may be circular.

FIG. 13 is a cross-sectional view of a self-contained side impact airbagsystem using an electro-mechanical sensor. An electro-mechanical sensoris one in which the sensing is accomplished through the motion of asensing mass from a first at-rest position to a second activatingposition at which point an event happens which typically involves theclosing of a switch by mechanical or magnetic means. In the embodimentshown in FIG. 13, biasing spring contact 1301 is caused to engagecontact 1302 arranged on an inside of the top cover 1350 when the sensorexperiences a crash as described above, i.e., acceleration of the sensorhousing 1310 above a predetermined threshold value which results inmovement of the sensing mass 1341 until the biasing contact 1301contacts the other contact 1302. Specifically, the biasing springcontact 1301 is positioned in a position (e.g., bearing against sensingmass 1341 in sensor housing 1310) so that it is moved during a crashalong with movement of the sensing mass 1341 (to the left in FIG. 13) tothereby bring the biasing spring contact 1301 into contact with contact1302. An electrical circuit is thereby completed causing ignition of theprimer or squib and thereafter the igniter mix and propellant. As shownin FIG. 13, the structure of the sensor housing 1310, inflator assembly1312, mounting plate 1360 and sensing mass 1341 may be as describedabove in appropriate part.

The implementation of FIG. 13 is a preferred location for theself-contained airbag module of this invention. Naturally, some of theteachings of this invention can be practiced without necessitating aself-contained module. For some implementations, for example, it isdesirable to place the airbag module at some other location than thevehicle door. One such location, for example, is the vehicle seat. Forthis implementation, the crash sensor in general cannot be co-locatedwith the airbag module. Therefore, it can be mounted on the side of thevehicle or elsewhere as long as there is a sufficiently strong memberconnecting the crash sensor to the vehicle side such that there islittle or no plastic deformation between the sensor and the side of thevehicle. Thus, the sensor experiences essentially the same crash signalas experienced by the side of the vehicle. Through this technique, thesensor acts as if it were mounted on the side of the vehicle and yet thewiring does not have to go through the door and through the hinge pillarto the airbag module. In this way, the sensor can be mounted remote fromthe vehicle side and yet perform as if it were located on the vehicleside which is accomplished by using an extension of the sensor, whichcan be a structural member of the vehicle.

FIG. 14 is a cross-sectional view of a self-contained side impact airbagsystem using an electronic sensor that generates a signal representativeof the movement of a sensing mass. Unless otherwise stated orinconsistent with the following description of an airbag system with anelectronic sensor, the airbag system with an electronic sensor mayinclude the features of the airbag system described above and below. Anelectronic sensor is one in which the motion of the sensing mass istypically continuously monitored with the signal electronicallyamplified with the output fed into an electronic circuit which isusually a micro-processor. Electronic sensors typically useaccelerometers that usually make use of strain gauge or piezo-electricelements shown here as 1401. The piezo-electric element generates asignal representative of the movement of the sensing mass. Modernaccelerometers are sometimes micro-machined silicon and combined withother elements on an electronic chip. In electro-mechanical sensors, themotion of the sensing mass is typically measured in millimeters and ismuch larger than the motion of the sensing mass in electronic sensorswhere the motion is frequently measured in microns or portions of amicron. The signal representative of the motion of the sensing mass isrecorded over time and an algorithm in the micro-processor may bedesigned to determine whether the movement over time of the sensing massresults in a calculated value which is in excess of the threshold valuebased on the signal. The sensing mass may constitute part of theaccelerometer, e.g., the sensing mass is a micro-machined accelerationsensing mass. In this case, the microprocessor determines whether themovement of the sensing mass over time results in an algorithmicdetermined value that is in excess of the threshold value based on thesignal.

In embodiments using an electronic sensor, the inflator may include aprimer, which is part of an electronic circuit including theaccelerometer. In this case, if movement over time of the sensing massresults in a calculated value in excess of the threshold value, theelectronic circuit is completed thereby causing ignition of the primer.

When the term electrical as used herein it is meant to include bothelectro-mechanical and electronic systems.

FIG. 15 is a schematic of the electric circuit of an electro-mechanicalor electronic side impact airbag system. The self-contained moduleimplementation shown generally at 1500 contains a sensor assembly 1540and an airbag and inflator assembly 1510. The sensor assembly 1540contains a sensor 1541, a diagnostic module 1542, an energy storagecapacitor 1543, and a pair of diodes 1515 to prevent accidentaldischarge of the capacitor if a wire becomes shorted. The module iselectrically connected to a diagnostic monitoring circuit 1560 by wire1501 and to the vehicle battery 1570 by wire 1503. It is also connectedto the vehicle ground by wire 1502. The sensor, diagnostic and capacitorpower supplies are connected to the squib by wires 1505 through 1507.

In a basic configuration, the diagnostic monitoring circuit 1560 checksthat there is sufficient voltage on the capacitor 1543 to initiate theinflator in the event of an accident, for example, and if any of wires1501, 1502, 1503 or 1504 are severed. In this case, the diagnosticinternal to the self-contained module would not be necessary. In moresophisticated cases, the diagnostic module 1542 could check that thesquib resistance is within tolerance, that the sensor calibration iscorrect (through self testing) and that the arming sensor has notinadvertently closed. It could also be used to record that the armingsensor, discriminating sensor and airbag deployment all occurred in theproper sequence and record this and other information for futureinvestigative purposes. In the event of a malfunction, the diagnosticunit could send a signal to the monitoring circuitry that may be no morethan an indication that the capacitor was not at full charge.

A substantial improvement in the reliability of the system is achievedby placing the diagnostic module and backup power supply within the selfcontained airbag system particularly in the case of side impacts wherethe impact can take place at any location over a wide area. An impactinto a narrow pole at the hinge pillar, for example, might be sufficientto sever the wire from the airbag module to the vehicle power sourcebefore the sensor has detected the accident.

Most of the advantages of placing the sensor, diagnostic and backuppower supply within the self contained module can of course be obtainedif one or more of these components are placed in a second module inclose proximity to the self contained module. For the purposes ofelectro-mechanical or electronic self contained modules, therefore, asused herein, the terms “self contained module” or “self contained airbagsystem” will include those cases where one or more of the componentsincluding the sensor, diagnostic and backup power supply are separatefrom the airbag module but in close proximity to it. For example, in thecase of steering wheel mounted systems, the sensor and backup powersupply would be mounted on the steering wheel and in the case of sideimpact door mounted systems, they would be mounted within the door orseat. In conventional electrical or electronic systems, on the otherhand, the sensor, diagnostic module and backup power supply are mountedremote from the airbag module in a convenient location typicallycentrally in the passenger compartment such as on the tunnel, under theseat or in the instrument panel.

With the placement of the backup power supply in the self containedmodule, greater wiring freedom is permitted. For example, in some casesfor steering wheel mounted systems, the power can be obtained throughthe standard horn slip ring system eliminating the requirement of theribbon coil now used on all conventional driver airbag systems. For sideimpact installations, the power to charge the backup power supply couldcome from any convenient source such as the power window or door lockcircuits. The very low resistance and thus high quality circuits andconnectors now used in airbag systems are not required since even anintermittent or high resistance power source would be sufficient tocharge the capacitor and the existence of the charge is diagnosed asdescribed above.

Herein, the terms capacitor, power supply and backup power supply havebeen used interchangeably. Also, other energy storage devices such as arechargeable battery could be used instead of a capacitor. For thepurposes of this disclosure and the appended claims, therefore, the wordcapacitor will be used to mean any device capable of storing electricalenergy for the purposes of supplying energy to initiate an inflator.Initiation of an inflator will mean any process by which the filling ofan airbag with gas is started. The inflator may be either purepyrotechnic, stored gas or hybrid or any other device which provides gasto inflate an airbag.

FIG. 16 is a side view showing the preferred mounting of two selfcontained airbag modules 1601 and 1602 on the side on a two doorvehicle. Module 1601 is mounted inside of a door, whereby the sensorhousing 101 of module 1601 is most proximate the exterior of thevehicle, while module 1602 is mounted between the inner and outer sidepanels at a location other than the door, in this case, to protect arear seated occupant. Each of the modules has its own sensor and, in thecase of electrical self-contained systems, its own capacitor powersupply and diagnostic circuit. Any of the airbag systems disclosedherein may be mounted either inside a door or between inner and outerside panels of the vehicle at a location other than the door and for nonself-contained systems, the sensor can be mounted anywhere providedthere is a sufficiently strong link to the vehicle side so that thesensor is accelerated at a magnitude similar to the vehicle side crushzone during the first few milliseconds of the crash. In view of themounting of module 1602 between inner and outer panels of the vehicle ata location other than the door, the inner and outer panels are thusfixed relative to the vehicle frame and the module 1602 is also thusfixed relative to the frame. By contrast, the module 1601 mounted insidethe door is moved whenever the door is opened or closed.

Thus, disclosed above is a vehicle including a side impact crash sensor,a transfer structure interposed between the side of the vehicle and thesensor, and an occupant restraint device such as a side impact airbagsystem. When an object strikes the side of the vehicle, the transferstructure transfers the lateral force from the side of the vehicle tothe sensor. The side impact crash sensor detects the lateral force oracceleration applied to a side of the vehicle. The airbag system isconnected to the sensor and arranged to deploy based on the force oracceleration detected by the sensor. The transfer structure may be aplate, and is optionally arranged to account for a mismatch between thepoint of impact of an object on the side of the vehicle and the sensor.The plate may be mounted on a main structural beam in the vehicle, suchas the main structural beam of the door of the vehicle. The entiresystem may be mounted between the inner and outer panels of the door ofthe vehicle. In another embodiment, there is a mismatch adjustment oraccounting structure in place of or in combination with the transferstructure.

The side impact crash sensor for a vehicle may include a housing, a masswithin the housing movable relative to the housing in response toaccelerations of the housing, means responsive to the motion of the massupon acceleration of the housing in excess of a predetermined thresholdvalue for controlling an occupant protection apparatus and means formounting the housing in such a position and a direction as to sense animpact into a side of the vehicle. The sensor may be an electronicsensor arranged to generate a signal representative of the movement ofthe mass and optionally comprise a micro-processor and an algorithm fordetermining whether the movement over time of the mass as processed bythe algorithm results in a calculated value which is in excess of thethreshold value based on the signal. In the alternative, the mass mayconstitute part of an accelerometer, i.e., a micro-machined accelerationsensing mass. The accelerometer could include a piezo-electric elementfor generating a signal representative of the movement of the mass.

With respect to the arrangement of the sensor, some non-limitingmounting locations include: 1) inside a door of the vehicle, 2) betweeninner and outer panels not associated with a door of the vehicle, 3) ina seat in the vehicle and 4) at a location remote from the side of thevehicle in which case, the vehicle should include a sufficiently strongmember connecting the sensor to the vehicle side such that there islittle or no plastic deformation between the sensor and the side of thevehicle.

Another embodiment of the sensor comprises a sensor assembly responsiveto a side impact for controlling the occupant protection apparatus,i.e., the airbag(s). The sensor assembly comprises a sensor housing, amass arranged within the sensor housing and movable relative to thehousing in response to acceleration thereof and means responsive to themovement of the mass upon acceleration of the housing in excess of apredetermined threshold value for controlling deployment of theairbag(s). The assembly may be mounted onto a side door of the vehicleand/or a side of the vehicle between the centers of the front and rearwheels of the vehicle in such a position and a direction as to causemovement of the mass upon an impact into the side of the vehicle.Additional mounting possibilities include in contact with a side doorassembly of the vehicle and/or a side panel assembly of the vehiclebetween the centers of the front and rear wheels in such a position anda direction as to cause movement of the mass upon an impact into theside of the vehicle.

One embodiment of a side impact airbag system for a vehicle inaccordance with the invention comprises an airbag housing defining aninterior space, one or more inflatable airbags arranged in the interiorspace of the system housing such that when inflating, the airbag(s)is/are expelled from the airbag housing into the passenger compartment(along the side of the passenger compartment), and an inflator forinflating the airbag(s). The inflator usually comprises an inflatorhousing containing propellant. The airbag system also includes a crashsensor as described above for controlling inflation of the airbag(s) viathe inflator upon a determination of a crash requiring inflationthereof, e.g., a crash into the side of the vehicle along which theairbag(s) is/are situated. The crash sensor may thus comprise a sensorhousing arranged within the airbag housing, external of the airbaghousing, proximate to the airbag housing and/or mounted on the airbaghousing, and a sensing mass arranged in the sensor housing to moverelative to the sensor housing in response to accelerations of thesensor housing resulting from, e.g., the crash into the side of thevehicle. Upon movement of the sensing mass in excess of a thresholdvalue, the crash sensor controls the inflator to inflate the airbag(s).The threshold value may be the maximum motion of the sensing massrequired to determine that a crash requiring deployment of the airbag(s)is taking place.

The crash sensor of this embodiment, or as a separate sensor of anotherembodiment, may be an electronic sensor and the movement of the sensingmass is monitored. The electronic sensor generates a signalrepresentative of the movement of the sensing mass that may be monitoredand recorded over time. The electronic sensor may also include amicroprocessor and an algorithm for determining whether the movementover time of the sensing mass as processed by the algorithm results in acalculated value that is in excess of the threshold value based on thesignal.

In some embodiments, the crash sensor also includes an accelerometer,the sensing mass constituting part of the accelerometer. For example,the sensing mass may be a micro-machined acceleration sensing mass, inwhich case, the electronic sensor includes a micro-processor fordetermining whether the movement of the sensing mass over time resultsin an algorithmic determined value which is in excess of the thresholdvalue based on the signal. In the alternative, the accelerometerincludes a piezo-electric element for generating a signal representativeof the movement of the sensing mass, in which case, the electronicsensor includes a micro-processor for determining whether the movementof the sensing mass over time results in an algorithmic determined valuewhich is in excess of the threshold value based on the signal.

The inflator may be any component or combination of components which isdesigned to inflate an airbag, preferably by directing gas into aninterior of the airbag. One embodiment of the inflator may comprise aprimer. In this case, the crash sensor includes an electronic circuitincluding the accelerometer and the primer such that if movement overtime of the sensing mass results in a calculated value in excess of thethreshold value, the electronic circuit is completed thereby causingignition of the primer.

Another embodiment of a side airbag system in accordance with theinvention includes an airbag arranged to deploy in the event of animpact into a side of the vehicle, a side impact crash sensor arrangedto sense an impact into a side of the vehicle, and an inflator forinflating the airbag. The crash sensor is an electrical sensor whichincludes a movable sensing mass which moves when the side of the vehicleis impacted and a signal generating mechanism for generating atime-varying signal representative of movement of the sensing mass,analyzing the signal representative of the movement of the sensing massand generating a deployment signal based thereon. The inflator iscoupled to the crash sensor and receives the deployment signal therefromand inflates the airbag upon receipt of the deployment signal. Thesignal generating mechanism may comprise a micro-processor whichprocesses signals representative of the continuous movement of thesensing mass. The movement of the sensing mass may be recorded over timewhile the micro-processor includes an algorithm arranged to determinewhether the movement of the sensing mass results in a calculated valuewhich is in excess of a threshold value in order to generate thedeployment signal. The electrical sensor may also comprise anaccelerometer. The signal generating mechanism may comprise a straingauge or a piezo-electric element. The airbag may be arranged around theinflator and the crash sensor may be arranged proximate the inflator.

A vehicle in accordance with the invention has a front, a rear, left andright sides and at least one door arranged on each of the left and rightsides, an airbag arranged to deploy along the left or right side of thevehicle in the event of an impact into the left or right side of thevehicle, a side impact crash sensor arranged to sense an impact into theleft or right side of the vehicle, and an inflator for inflating theairbag. The crash sensor, as well as the other components of thevehicle, may be as described above.

A method for protecting an occupant in a vehicle comprises arranging anairbag in the vehicle in a position to protect the occupant in the eventof an impact into a side of the vehicle, sensing an impact into a sideof the vehicle by continuously monitoring movement of a sensing mass togenerate a time-varying signal representative of movement of the sensingmass and analyzing the signal representative of the movement of thesensing mass to generate a deployment signal based thereon, anddirecting the deployment signal to an inflator to cause the inflator toinflate the airbag. A micro-processor processes the signalrepresentative of the movement of the sensing mass and optionallyincludes an algorithm arranged to determine whether the motion over timeof the sensing mass results in a calculated value which is in excess ofa threshold value in order to generate the deployment signal.

Although several preferred embodiments are illustrated and describedabove, there are possible combinations using other geometries, materialsand different dimensions for the components that can perform the samefunction. For example, the biasing spring need not be the same as thebiasing spring in the case of the implementation shown in FIG. 1 and amagnet might be used in place of a biasing spring for several of themechanical cases illustrated. Therefore, this invention is not limitedto the above embodiments and should be determined by the followingclaims.

1. In a vehicle having a longitudinal axis between a front and rear ofthe vehicle such that a lateral direction is defined perpendicular tothe longitudinal axis, the vehicle including a right side and a leftside spaced apart in the lateral direction, a side impact airbag systemcomprising a side airbag arranged to deploy along the left or right sideof the vehicle; and an electronic crash sensor comprising: a housing; amass arranged within said housing in a position and direction so as tobe movable in the lateral direction relative to said housing in responseto lateral accelerations of said housing; and a control mechanism forcontrolling deployment of said side airbag, said control mechanism beingresponsive to the motion of said mass only in the lateral direction;said housing being mounted in such a position and a direction as tosense an impact into a side of said vehicle resulting in lateralacceleration of said housing.
 2. The vehicle of claim 1, wherein saidelectronic crash sensor is arranged to generate a signal representativeof the movement of said mass.
 3. The vehicle of claim 1, wherein saidelectronic crash sensor comprises a microprocessor and an algorithm fordetermining whether movement over time of said mass results in acalculated value which is in excess of a threshold value.
 4. The vehicleof claim 1, wherein the right and left sides of the vehicle each includea door and said housing is arranged inside the door.
 5. A vehicle,comprising a longitudinally extending outer skin arranged on a side ofthe vehicle; a system housing arranged inward of said outer skin andhaving an opening facing a portion of a passenger compartment of thevehicle; an inflatable airbag arranged in said system housing; aninflator arranged in connection with the system housing; and anelectronic sensor system for detecting an impact into a side of to thevehicle and comprising a sensor housing and a mass arranged in saidsensor housing and movable relative to said sensor housing in responseto acceleration, movement of said mass relative to said sensor housingproviding an indication of a side impact for which deployment of saidairbag is desired; said inflator being actuated in response to adetected side impact by said sensor system in order to expel said airbagthrough said opening into the passenger compartment, and wherein saidsensor system is arranged such that said inflator is actuated and saidairbag is inflated and expelled through said opening into the passengercompartment based on movement of said mass.
 6. The vehicle of claim 5,further comprising an inner skin having a portion alongside thepassenger compartment of the vehicle, said system housing being arrangedbetween said outer and inner skins of the vehicle and said opening ofsaid system housing being situated on an inward facing side of saidsystem housing, said system housing being mounted such that said openingfaces an outward facing surface of said inner skin alongside thepassenger compartment.
 7. The vehicle of claim 5, wherein said inflatoris arranged at least partially within said system housing.
 8. Thevehicle of claim 1, wherein said inflator is arranged on a side of saidsystem housing opposite the side on which said opening is formed.
 9. Thevehicle of claim 1, wherein said system housing includes a base wallhaving an aperture in which the inflator is partially received andflanged walls extending from edges of said base wall and forming saidopening.
 10. The vehicle of claim 1, wherein said inflator includes aplurality of gas orifices, said airbag being inflated by directinginflating gas through said orifices into said airbag.
 11. The vehicle ofclaim 1, wherein said sensor system is arranged on a side of said systemhousing opposite the side on which said opening is formed.
 12. Thevehicle of claim 11, wherein said sensor system is arranged proximatesaid inflator or alongside said inflator.
 13. The vehicle of claim 1,wherein said sensor system is arranged outside of and on said inflator.14. A method for deploying a side airbag of a vehicle having an outerskin, comprising: providing a system housing having an opening; mountingthe system housing with the opening facing a portion of a passengercompartment of the vehicle; arranging an inflatable airbag in the systemhousing; arranging an inflator in connection with the system housing;electronically sensing a side impact by detecting motion of a masssituated in a sensor housing relative to the sensor housing and inresponse to acceleration; actuating the inflator in response to thedetected side impact to expel the airbag through the opening in thesystem housing into the passenger compartment; and coupling the mass tothe inflator such that the inflator is actuated always upon sensing ofthe side impact above a certain magnitude in a direction perpendicularto the outer skin of the vehicle.
 15. The method of claim 14, furthercomprising arranging the system housing between the outer skin and aninner skin of the vehicle such that the opening of the system housing ison an inward facing side of the system housing, the system housing beingmounted such that the opening faces an outward facing surface of theinner skin alongside the passenger compartment.
 16. The method of claim14, wherein the outer and inner skins form a door, further comprisingarranging the system housing in the door.
 17. A vehicle, comprising: alongitudinally extending outer skin arranged on a side of the vehicle; asystem housing arranged inward of said outer skin and having an openingfacing a portion of a passenger compartment of the vehicle; aninflatable airbag arranged in said system housing; an inflator arrangedin connection with the system housing; and an electronic sensor systemfor detecting an impact into a side of the vehicle and comprising asensor housing and a mass arranged in said sensor housing and movablerelative to said sensor housing in response to acceleration, movement ofsaid mass relative to said sensor housing providing an indication of aside impact for which deployment of said airbag is desired; saidinflator being actuated in response to a detected side impact by saidsensor system in order to expel said airbag through said opening intothe passenger compartment, and wherein said inflator is actuateddirectly by said sensor system whenever said sensor system provides anindication of the side impact in a direction perpendicular to said outerskin of the vehicle for which deployment of said airbag is desired. 18.In a vehicle having front and rear wheels and a longitudinal axisbetween a front and rear of the vehicle such that a lateral direction isdefined perpendicular to the longitudinal axis, the vehicle also havingleft and right sides, a side impact airbag system comprising: an airbagand inflator assembly including an airbag housing, at least oneinflatable airbag arranged in said airbag housing such that wheninflating, said at least one airbag is expelled from said airbag housinginto a passenger compartment of the vehicle; and a squib arranged toinitiate inflation of said at least one airbag; and an electronic sensorsystem for controlling inflation of said at least one airbag upon adetermination of a crash into the left or right side of the vehiclerequiring inflation of said at least one airbag and including a sensorhaving a sensor housing arranged in a door or between inner and outerside panels along the left or right side of the vehicle and a movablesensing mass arranged within and movable in the lateral directionrelative to said sensor housing in response to lateral accelerations ofsaid sensor housing; and at least one electronic component responsive tothe motion of said mass and arranged in a circuit with said squib forcausing ignition of said squib; said sensor housing being arranged insuch a position and a direction in the door or between the inner andouter panels along the left or right side of the vehicle as to causemovement of said mass upon an impact into the left or right side of saidvehicle resulting in lateral acceleration of said sensor housing. 19.The vehicle of claim 18, wherein said at least one electronic componentis a micro-processor containing an algorithm arranged to generate atime-varying signal representative of movement of said mass in thelateral direction, analyze the signal representative of the movement ofsaid mass and generate a deployment signal based thereon.
 20. Thevehicle of claim 18, wherein said sensor housing is mounted onto a sidedoor of the vehicle or onto a side of the vehicle between centers offront and rear wheels of the vehicle.